Articular cartilage is a type of hyaline cartilage that lines the surfaces of the opposing bones in a diarthrodal joint (e.g. knee, hip, shoulder, etc.). Articular cartilage provides a near frictionless articulation between the bones, while also functioning to absorb and transmit the compressive and shear forces encountered in the joint. Further, since the tissue associated with articular cartilage is aneural, these load absorbing and transmitting functions occur in a painless fashion in a healthy joint.
Human joints also have another type of cartilage present: intra-articular fibrocartilage. Intra-articular fibrocartilage can be present in the form of a discus articularis, that is, as a plate or ring of fibrocartilage in the joint capsule separating the joint surfaces (articular cartilage) of the bones of the joint. Such fibrocartilage is present, for example, in the temporomandibular joint, between vertebrae, and in the knee joint. In the knee joint, the intra-articular fibrocartilage comprises the meniscus, a crescent-shaped or semi-lunar-shaped disc of tissue that is located between the femoral condyles and the tibial plateau. The meniscus primarily functions as a shock absorber, absorbing the shock of compressive and shear forces in the knee. The meniscus also provides a substantially frictionless surface for articulation of the knee joint.
When cartilage tissue is no longer healthy, there can be debilitating pain in the joint. Cartilage health can be adversely affected by disease, aging, or trauma. The adverse effects of disease, aging and trauma can be in the form of a tear in the cartilage or in the form of a breakdown of the cartilage matrix.
In the knee, the meniscus is frequently damaged in twisting injuries. It is also damaged with repetitive impact over time. Meniscus degeneration can also occur by aging; as a person ages, the meniscus can become soft in places, so that even common motions like squatting can cause meniscal tears.
Common surgical procedures for treating meniscal damage include tear repairs and meniscectomies. A tear repair is most commonly performed when the tear is a clean longitudinal vertical lesion in the vascular red zone of the meniscus. The basic strategy is to stabilize the tear by limiting or eliminating radial separation of the faces of the tear when the meniscus is load bearing. Many devices and surgical procedures exist for repairing meniscal tears by approximating the faces of the meniscus at the tear. Examples of such devices and procedures are disclosed in the following U.S. Pat. Nos. 6,319,271; 6,306,159; 6,306,156; 6,293,961; 6,156,044; 6,152,935; 6,056,778; 5,993,475; 5,980,524; 5,702,462; 5,569,252; 5,374,268; 5,320,633; and 4,873,976.
Meniscectomies involve the surgical removal of part of the meniscus. Such procedures have generally been performed in cases of radial tears, horizontal tears, vertical longitudinal tears outside the vascular zone, complex tears, or defibrillation. Although meniscectomies provide immediate relief to the patient, in the long term the absence of part of the meniscus can cause cartilage wear on the condylar surface, eventually leading to arthritic conditions in the joint.
U.S. Pat. No. 6,042,610 assigned to ReGen Biologics, Inc., hereby incorporated by reference, discloses the use of a collagen scaffold device comprising a bioabsorbable material made at least in part from purified natural fibers. The purified natural fibers are cross-linked to form the device of that patent. The device produced can be used to provide augmentation for a damaged meniscus. Related U.S. Pat. Nos. 6,042,610; 5,735,903; 5,681,353; 5,306,311; 5,108,438; 5,007,934; 4,880,429 also disclose a meniscal augmentation device for establishing a scaffold adapted for ingrowth of meniscal fibrochondrocytes.
It is also known to use naturally occurring extracelluar matrices (ECMs) to provide a scaffold for tissue repair and regeneration. One such ECM is small intestine submucosa (SIS). SIS has been described as a natural biomaterial used to repair, support, and stabilize a wide variety of anatomical defects and traumatic injuries. See, for example, Cook® Online News Release provided by Cook Biotech Inc. at “www.cookgroup.com”. The SIS material is derived from porcine small intestinal submucosa that models the qualities of its host when implanted in human soft tissues. Further, it is taught that the SIS material provides a natural matrix with a three-dimensional structure and biochemical composition that attracts host cells and supports tissue remodeling. SIS products, such as OASIS™ and SURGISIS™, are commercially available from Cook Biotech Inc., Bloomington, Ind.
Another SIS product, RESTORE® Orthobiologic Implant, is available from DePuy Orthopaedics, Inc. in Warsaw, Ind. The DePuy product is described for use during rotator cuff surgery, and is provided as a resorbable framework that allows the rotator cuff tendon to regenerate. The RESTORE Implant is derived from porcine small intestine submucosa, a naturally occurring ECM composed primarily of collagenous proteins, that has been cleaned, disinfected, and sterilized. Other biological molecules, such as growth factors, glycosaminoglycans, etc., have also been identified in SIS. See: Hodde et al., Tissue Eng., 2(3): 209-217 (1996); Voytik-Harbin et al., J. Cell. Biochem., 67: 478-491 (1997); McPherson and Badylak, Tissue Eng., 4(1): 75-83 (1998); Hodde et al., Endothelium 8(1): 11-24; Hodde and Hiles, Wounds, 13(5): 195-201 (2001); Hurst and Bonner, J. Biomater. Sci. Polym. Ed., 12(11): 1267-1279 (2001); Hodde et al., Biomaterial, 23(8): 1841-1848 (2002); and Hodde, Tissue Eng., 8(2): 295-308 (2002). During seven years of preclinical testing in animals, there were no incidences of infection transmission from the implant to the host, and the SIS material has not adversely affected the systemic activity of the immune system. See: Allman et al., Transplant, 17(11): 1631-1640 (2001); Allman et al., Tissue Eng., 8(1):53-62 (2002).
While small intestine submucosa is available, other sources of ECM are known to be effective for tissue remodeling. These sources include, but are not limited to, stomach, bladder, alimentary, respiratory, and genital submucosa. In addition, liver basement membrane is known to be effective for tissue remodeling. See, e.g., U.S. Pat. Nos. 6,379,710, 6,171,344, 6,099,567, and 5,554,389, hereby incorporated by reference. Further, while ECM is most often porcine derived, it is known that these various ECM materials can be derived from non-porcine sources, including bovine and ovine sources. Additionally, the ECM material may also include partial layers of laminar muscularis mucosa, muscularis mucosa, lamina propria, stratum compactum layer and/or other such tissue materials depending upon other factors such as the source from which the ECM material was derived and the delamination procedure.
The following patents, hereby incorporated by reference, disclose the use of ECMs for the regeneration and repair of various tissues: U.S. Pat. Nos. 6,379,710; 6,187,039; 6,176,880; 6,126,686; 6,099,567; 6,096,347; 5,997,575; 5,993,844; 5,968,096; 5,955,110; 5,922,028; 5,885,619; 5,788,625; 5,733,337; 5,762,966; 5,755,791; 5,753,267; 5,711,969; 5,645,860; 5,641,518; 5,554,389; 5,516,533; 5,460,962; 5,445,833; 5,372,821; 5,352,463; 5,281,422; and 5,275,826.